[allocbox-to-stack] When we promote an argument that is moveonly, use consumable_and_assignable, not assignable_but_not_consumable.

Otherwise, since the compiler views assignable_but_not_consumable in this
position as a sign of an escaping closure, we emit escaping closure errors
instead of nonescaping closure errors.

lib/SILOptimizer/Transforms/AllocBoxToStack.cpp

@@ -1041,7 +1041,7 @@ specializeApplySite(SILOptFunctionBuilder &FuncBuilder, ApplySite Apply,
         auto boxType = F->getArgument(index)->getType().castTo<SILBoxType>();
         bool isMutable = boxType->getLayout()->getFields()[0].isMutable();
         auto checkKind =
-            isMutable ? MarkMustCheckInst::CheckKind::AssignableButNotConsumable
+            isMutable ? MarkMustCheckInst::CheckKind::ConsumableAndAssignable
                       : MarkMustCheckInst::CheckKind::NoConsumeOrAssign;
         hoistMarkMustCheckInsts(ClonedFn->getArgument(index), checkKind);
       }